feat: codex channel (#2652)

* feat: codex channel

* feat: codex channel

* feat: codex oauth flow

* feat: codex refresh cred

* feat: codex usage

* fix: codex err message detail

* fix: codex setting ui

* feat: codex refresh cred task

* fix: import err

* fix: codex store must be false

* fix: chat -> responses tool call

* fix: chat -> responses tool call

relay/channel/codex/constants.go

@@ -0,0 +1,9 @@
+package codex
+
+var ModelList = []string{
+	"gpt-5", "gpt-5-codex", "gpt-5-codex-mini",
+	"gpt-5.1", "gpt-5.1-codex", "gpt-5.1-codex-max", "gpt-5.1-codex-mini",
+	"gpt-5.2", "gpt-5.2-codex",
+}
+
+const ChannelName = "codex"